The invention concerns a catheter for the introduction into blood vessels having a lumen and guide means arranged therein.
In this description the term catheter is also used for example to denote an electrode together with electrode line for cardiac pacemakers or defibrillators. A large number of various catheters of the kind set forth in the opening part of this specification are known, which are equipped with various guide means in order to direct a catheter through blood vessels to a desired location. Such catheters or electrodes are known for example from EP 0 667 126, U.S. Pat. Nos. 5,423,884, 5,367,109 or DE 35 107 119.
It has been found that known catheters, in particular known cardiac pacemaker electrodes, are scarcely suitable for being introduced for example into the coronary sinus of a heart. There is however the wish to be able also to introduce in particular a cardiac pacemaker electrode into the coronary sinus or blood vessels which involve similar difficulties of access.
Therefore the object of the present invention is to provide a catheter which is suitable for introduction into the coronary sinus or other blood vessels which involve difficult access, in particular a cardiac pacemaker electrode line.
In accordance with the invention, that object is achieved with a catheter of the kind set forth in the opening part of this specification, in which the guide means include a pre-bent wire displaceable in the longitudinal direction of the catheter and in which the catheter has at its distal end an exit lock means such that the prebent wire can issue from the catheter through the exit lock means at the distal end.
The invention is based on the notion of using the pre-bent wire as a probe which can be advanced beyond the tip of the catheter and which, by virtue of the prebent configuration of the wire, faces in a direction which differs from the straight-ahead direction of the catheter. It is possible In that way with the pre-bent wire, to advance into a branch of the blood vessels and to follow with the catheter which is then guided by the pre-bent wire. In this case, the pre-bent wire can be retracted into the catheter again to the same degree as the catheter is advanced so that the tip of the pre-bent wire does not need to execute any relative movement with respect to the blood vessel when the catheter follows along. An exit lock means at the tip of the catheter makes it possible to push out the pre-bent wire without any amount of body fluid worth mentioning penetrating into the catheter.
The pre-bent wire is preferably a spring steel wire. It is pre-bent in a helical or spiral configuration at least in the region of its distal end. That manner of pre-bending the wire makes it possible to afford various orientations for the wire, depending on how far the wire is advanced beyond the tip of the catheter. Spring steel wire is suitable for the reason that spring steel can be pre-bent and then the spring action of the spring steel can be straightened out again under the influence of suitable return forces, in which case when those return forces are released, the spring steel wire resumes its pre-bent shape.
Preferably the guide means include for the pre-bent wire a guide sleeve or casing which is of such a configuration that it holds the pre-bent wire within the catheter in a straight prestressed condition. The guide sleeve, for example a tube portion, into which the pre-bent wire is inserted, in this case exerts the return forces required for straightening the spring steel wire. When the spring steel wire is advanced out of the tube portion, those return forces which are exerted on the spring steel wire by the tube portion no longer act so that the spring steel wire curves in a configuration corresponding to its pre-bent shape as soon as it issues from the guide sleeve.
In this case, the pre-bent wire is preferably adapted to be rotatable relative to the rest of the catheter about its longitudinal axis and is connected to actuating means arranged at the proximal end of the catheter, for rotation of the pre-bent wire. If the pre-bent wire is pre-bent for example in a spiral configuration, it is possible by way of the actuating means to determine the radial direction in which the pre-bent wire is oriented upon being advanced beyond the tip of the catheter.
Preferably the catheter has a bar which is of a tubular configuration and which serves as a guide sleeve or casing, having an internal passage in which the pre-bent wire is guided. In that way the bar holds the guide wire oriented in the longitudinal direction of the catheter. The bar is preferably also arranged longitudinally slidably in the catheter and/or rotatably about its longitudinal axis and is connected to actuating means for producing the longitudinal sliding movement and/or the rotary movement of the bar. The pre-bent wire which is guided in the bar can also be rotated in the same way with the actuating means for rotating the bar so that the orientation of the pre-bent wire can be determined by way of the rotary movement of the bar. If the bar is for example in the form of a stylet for screwing in a screw-in tip for an electrode line, the bar and the pre-bent wire can also be adapted to be rotatable independently of each other.
Preferably the exit lock means includes a diaphragm or membrane which is to be pierced by the pre-bent wire. In that way the tip of the catheter can remain completely closed by the diaphragm until the pre-bent wire pierces the diaphragm and issues from the tip of the cathode at the front thereof. If the diaphragm comprises elastic material, for example silicone, it closes again when the pre-bent wire is retracted into the catheter again.
On its side towards the interior of the catheter the exit lock means preferably has an entrance opening for the pre-bent wire, which opening is of a funnel-shaped configuration. That makes it easier to introduce the tip of the pre-bent wire into the exit lock means.
The exit lock means preferably also has an exit opening in the outside of the catheter, which is in the center of a rounded catheter tip at the distal end of the catheter. Due to the central arrangement of the exit opening on the tip of the catheter, the orientation of the catheter itself, upon extension of the pre-bent wire, is irrelevant, the catheter behaves in the same manner in any rotational angular position. The rounded tip of the catheter contributes to the catheter being able to easily follow the pre-bent wire when following same, even in lateral blood vessels which involve a difficult access.
The pre-bent wire is preferably coated with gold so that it can be located for example by an X-ray device so that the pre-bent wire can be specifically controlled upon insertion of the catheter.
The catheter is preferably in the form of a cardiac pacemaker or defibrillator electrode.